The present invention relates to washing and sanitizing of surfaces such as food-preparation areas, piping, industrial equipment, and storage tanks; and more particularly to systems that utilize ozone as the sanitizing agent.
The beneficial properties of ozone have been recognized and applied for many decades. Ozone has been used as a disinfectant to destroy bacteria and certain viruses in drinking water and in air, as a deodorizer for air and sewage gases, as a bleach, and as an oxidizing agent in various chemical processes. Typically, ozone is utilized as a gas or dissolved in water.
The use of ozone as a sterilant has heretofore been confined largely to specialty applications, e.g., flow-through disinfecting of dialysis equipment (see U.S. Pat. No. 5,641,456) and sterilization of medical instruments (see U.S. Pat. No. 5,520,893). More widespread adoption of ozone cleaning equipment has been hampered by the constraints involved in creating and delivering aqueous ozone solutions.
Ozone, or O3, is an unstable molecule that may be formed by subjecting ordinary molecular oxygen to ultraviolet radiation or to forms of electric discharge (such as coronas and sparks). Ozone quickly breaks down, reverting to molecular oxygen or reacting with surrounding species, and so cannot easily be stored; for a system to be practical, ozone must be generated on site at the time of use. Moreover, because of its reactivity, ozone cannot be combined with detergents or other cleaning agents, since the these are vulnerable to ozone attack; in effect, the ozone will destroy both its own effectiveness and that of the cleaning agent rather than attacking pathogens. Consequently, the delicate nature of the ozone molecule and its incompatibility with conventional cleaning agents has limited the applications of ozone cleaning.
In accordance with the present invention, the benefits of detergent cleaning are combined with ozone disinfection in a single, preferably mobile sanitizing unit. The invention provides means for directing a detergent cleaning solution, preferably under pressure, onto a surface to be cleaned. The invention also provides an aqueous ozone rinse, which is applied to the surface following removal of soils by the detergent. Because the ozone rinse functions to sanitize the target and remove residual detergent, and works best when delivered without substantial pressure, construction and ozone generation are simplified.
The invention is usefully employed to sanitize food-preparation areas, piping, industrial equipment, and storage tanksxe2x80x94virtually any exposed surface not harmed by moisture but capable of accumulating soils and harboring harmful pathogens. Ozone decomposes quickly following application, so the ozonated aqueous rinse stream leaves no harmful residues or toxic byproducts. To ensure a high degree of sterilization, the ozone should be present in the rinse stream in an amount ranging from 0.1 ppm to 1.5 ppm, and preferably approximately 0.7 ppm.
The invention also provides a method of cleaning and sanitizing a surface, the method comprising the steps of providing a source of cleaning solution (which is generally detergent-based) and a source of ozonated water, cleaning the surface by selectively directing the cleaning solution onto the surface under pressure, and rinsing the surface by selectively directing a flow of the ozonated water onto the surface.